Regulations require that automobiles contain a catalyst detection system as part of the automobile's exhaust aftertreatment system to insure compliance with emission requirements. Catalysts in an exhaust aftertreatment system, such as an SCR catalyst, can be intentionally removed or not installed during assembly. Catalysts are key elements for the reduction of exhaust emissions and must be present for the exhaust aftertreatment system to work as intended. A missing catalyst may cause excessive nitrogen oxide (NOx) emission, excessive urea emission, potential NOx sensor damage, and/or other negative consequences.
Automatically detecting the presence of a catalyst in an exhaust aftertreatment system is often hindered due to the difficulty of distinguishing between common catalyst indicators and other problems within the exhaust aftertreatment system, such as a clogged urea doser and poor urea quality. When a diagnostic incorrectly identifies a missing catalyst that is in fact present, time and resources are unnecessarily spent to inspect the automobile only to find that the diagnostic has incorrectly indicated a missing catalyst.
Additionally, current methods of automatic catalyst detection may require that the automobile perform a cold soak prior to testing. Cold soaks require a long period of engine inactivity, which may take several hours and require extended engine-off time. This significantly decreases the in-use ratio of the automobile and the catalyst detection device.
Other known methods for detecting the presence of a catalyst using sensors can be ineffective due to the negative consequences associated with sensor uncertainties and miscalibration.